Machine tool



B. R. PURVIN MACHINE TOOL Jaan.v ll, 1944.

l0 ShetS-Sheet 1 Filed Feb. 5, 1940 'INVENTOR enjam n R. Pam/n l @n MM( TTORNEYS BY @www Jan. 11, 1944.i B. R. pum/1N MACHINE TOOL Filed Feb. 5, 1940 l0 Sheets-Sheet 4 INV'ENTOR f, Ber/januri R. PLI/*Vin f BY 65 m L11/iw, @zu .1W

A TORNEYS Jan. 11, 1944. B R, PURVIN 2,338,737

MACHINE TOOL Filed Feb. 3, 1940 1o shets-sneet 5 -|NvENToR efyamzn R, Puri/f1 BY y. (7d/:hr1 $4 ATTORNEYS Jan. 11, 1944. B, R PURVIN 2,338,737

MACHINE TOOL Filed Feb. 3, 1940 lO SheetS-Sheetl 6 Bef/'amm R. Pam/H Y @be M@ Hf@ .4440( ATTORNEYS Jan. 11, 1944.

B. R. PuRvlN 2,338,737

MACHINE TOOL Filed Feb. s, 1940 1o sheets-sheet fr 4 INVENTOR .Be/Uamzw R. Puff/h .BY M M @fau pw 'TTORNYS B. R. PU RVlN MACHINE TOOL Jan. 11, 1944.

' 1o sheets-sheet 8 Filed Feb. 3, 1940 INVENTOR BerZ/'urr/n R.

Pam/[f1 AT RNEYS Jan- 11, 1944- B. R. PURVIN 2,338,737

MACHINE TOOL Filed Feb. 3, 1940 l0 Sheets-Sheet 9 /zz so@ 46 4&1

'INVENTOR .Benjamin R Pari/77 u i BY @be Mm,

Jan. 11, 1944.

B. R. PURVIN MACHINE TOOL Filed Feb. 3, 1940 l0 Sheets-Sheet lO lg. Z

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UNITED' STATES PATENT oFFlcEf MACHINE TOOL Benjamin R. Purvin, Rockford, Ill., assig-nor to Barber-Colman Company, Rockford, Ill., a corporation of Illinois Application February 3, 1940, Serial No. 317,166

35 Claims.

such manner that in the machining operations close tolerances are accurately maintained and an improved finish is produced.

.Another object of the invention is to provide a novel machine in which the movements of the machine elements and the control thereof are obtained by combined or interconnected electrically and hydraulically actuated means.

A further object is to provide in a machine of this character new and improved means for controlling movements of the machine elements which embodies electric power means for driving the elements during a cutting operation, hydraulic power means for moving the elements into operative relation and establishing the driving connections, and a, combination of electrically and hydraulically responsive means for controlling cyclic `operation including rapid traverse or return and for controlling various non-@cyclic movements of the machine elements.

Another object is to provide new and improved means for initiating and controlling cyclic operation including the movement of the machine elements into operative relation, effecting relative spindle translation in one direction with a feeding movement, automatically discontinuing such movement at the end of the out, effecting'a rapid return movement, automatically discontinuing the return movement at the initial or starting position and retracting the machine elements to their relative inoperative relation.

In conjunction with the foregoing, an object is to provide in the machine control system novel means which enable the operator to perform the following manipulative acts: (1) stop a cycle at will and either return the machine elements to their starting position, or maintain the elements in the relation in which they are stopped for subsequent resumption of the cycle; (2) control ,the main driving clutch independently of the cycle; (3) rapidly traverse the spindles relatively only when the machine elements will not be damaged by such movement; and (4) conveniently and quickly adapt the machine elements for conventional or climb cutting with feed in either direction, and set the control mechanism to correspond.

Other objects and advantages will become apparent in the following description and from the accompanying drawings, in which:

Figure 1 is a front elevational view of a machine tool embodying the features of the invention.

Fig. 2 is a sectional view through the swivel slide assembly taken substantially along the line 2 2 of Fig. l.

Fig. 3 is a sectional View of a detail of the swivel slide assembly taken substantially along the line 3 3 of Fig. 2.

Fig. 4 is a view ci the swivel slide assembly partly in plan and partly in section, as indicated by the line i of Fig. 5.

Fig. 5 is a side .view of the swivel slide partially broken away to illustrate the arrangement of the internally located clamping means.

Fig. 6 is a sectional view of a detail of the clamping means taken as indicated by the line 6 6 of Fig. 5.

. Fig. 7 is a sectional view through the machine tool below the swivel slide assembly on the vertical plane, indicated by the line 1-7 of Fig. 2.

Fig. 8 shows a detail of the feed screw and feed clutch assembly and is partly in section.

Fig. 9 is a sectional view through the work spindle assembly taken substantially on the plane of the axes of the work spindle and feed screw.

Figs. 10 and 11 are sectional Views illustrating the driving mechanism for the work spindle and feed screw, and are taken respectively along the transverse planes indicated by the lines Illl0 and Il-il of Fig. 9.

Fig. 12 is a diagrammatic representation of the driving mechanism of the machine tool.

Fig. 13 is a diagrammatic representation of the double ended control cam illustrating its operative relationship to the cam followers associated therewith.

Fig. 14 is a perspective view of the valve and switch control mechanism.

Fig. 15 is a sectional view through the control casing taken along the line I5-I5 of Fig. 1.

Figs. 16 and 17 are diagrammatic representations of the hydraulic and electrical control means. The gures may be combined to show the complete system by alinement of the right hand side of Fig. 16 with the left hand side of Fig. 17.

A machine organization in which an exemplary form oi' the invention is embodied comprises a base upon which is mounted a pair of spaced upright hollow columns rigidly tied together at the top by a bridge. One column supports a vertically reciprocable slide for the work spindle, and associated driving means for rotating the spindle and for feeding the slide. Preferably, a control panel and driving means for effecting a rapid traverse movement of the work slide is mounted on the same column. The opposite column supports a slide on which the tool spindle is mounted, and is horizontally reciprocable to move a tool into and out of operative relation to a work blank on the work spindle. The tool spindle is driven by a prime mover located in its associated column through intermediate driving connections which includes a branch power transmission leading to the work spindle and feed driving means.

The power drive'means and the control means therefor include a combination of hydraulically and electrically actuated mechanisms, in which the tool and work spindles and the feed means are driven from an electric motor as a prime mover, the rapid traverse is driven by a separate electric motor, the movements of the machine elements into and out of operative relation are hydraulically actuated, and the controls are interrelated hydraulic and electric means arranged to cause a cycle of machine operation which includes relative movement of the machine elements into operative relation, initiation of the spindle and feed drives, relative translation of the spindles to perform a working operation, automatic stop of feed upon completion of the cut, initiation of a rapid return movement, automatic stop when the elements have been returned to the starting position, and retraction of the machine elements to an inoperative relationship. The control means also permits auxiliary machine movements at the will of the operator when the machine elements have certain operative relationships and the relationships determine the character of the permitted auxiliary movements.

Referring more particularly to the exemplary machine illustrated in the drawings Aand with particular reference to Fig. 1, the numeral 20 designates a base from which vertical columns 2| and 22 rise near either end thereof. (For convenience in description the columns will be referred to as right-hand column 2| and lefthand column 22). Extending across the tops of the columns and secured thereto is a bridge 23. The base, the columns and the bridge define a central space or opening 24 in which the operative elements of the machine are disposed, and form a rigid supporting structure that is capable of withstanding, without yielding, the heavy stresses .imposed during a cutting operation such as hobbing. The tool and work spindles are so correlated that the stresses are mainly exerted generally in horizontal direction toward the two columns, which being firmly and rigidly tied together top and bottom cannot flex. This relationship is important since the resulting rigidity of the frame permits high speed machine operation with maintenance of close tolerances and production of unusually smooth finished surfaces.

In the present embodiment, the work spindle 25 is supported from the right-hand column by a vertically reciprocable slide 26 having associated therewith means for traversing the Work relative to the tool through feed and rapid traverse movements. Mounted on the left-hand column 22 is a tool support 23 for a tool T adapted for The tool supporting means (refer to Figs. 1 to 7 incl. and 12.)

The side of the left-hand column 22 which faces toward opposite column has an enlarged recess or opening 29 (Fig. 2) therein located substantially midway between the base 20 and the bridge 23. Horizontally disposed ways 30 extending inwardly of the opening 29 support -a ram or slide 3| which, for convenience, will hereinafter be termed the swivel slide, since it supports the means by which the position of the tool may b'e properly correlated with respect to the work.

The swivel slide 3| projects from the column 22 into the space 24, and is formed with an end wall 32 (Fig. 4) and externally thereof with an annular guide or way 33 having an annular T- slot 34. A slide swivel 35 is mounted for angular adjustment against the outer face of the way 33, and is adapted to be secured in position by means of clamp bolts (not shown) engaging in the T-slot 34. The slide swivel 35 has a short cylindrical centering boss 36 which interilts with the inner peripheral face of the way 33.

To provide meansfor adjusting the slide swivel 35, an arcuate worm gear segment 31 (Figs. 2 and 3) is suitably secured., as by screw bolts 38, coaxially to the inner end of the boss 36. The worm gear segment 31 meshes with a worm 39 keyed to a shaft 40 within a tangential bore 4| formed in the upper portion of the swivel slide 3| and opening to one side thereof. The outer end of the shaft 40 is journaled in and extends through a bearing sleeve 42 fixed in the outer end of the bore 4| as by means of a pin 43, and the inner end of the shaft is suitably journaled in the body of the slide. The extreme outer end of the shaft 40 is provided with a socketed head 44 adapted for the reception of a suitable hand tool (not shown). It will be seen that upon rotation of the shaft 40, the worm 39 will rotate the gear segment 31 to adjust the angular position of the swivel 35. The degree or extent of adjustment may be determined by meansof cooperative indicia 45 (Figs. 1 and 5) on mating edges of the annular way 33 and the swivel 35.

The outer face of the swivel 35 is formed with a diametrically extending dovetail guideway 4B (Figs. 4 and 5) for supporting a spindle slide 41. The position of the slide 41 is adjustable along the guideway 46 to effect operative engagement of different portions of the tool T with the work W. Thus, an adjusting shaft 48 (Fig. 4) is journaled on the swivel 35 longitudinally of the guideway 4B, the outer end portion of the shaft extending through a fixed bearing sleeve 49, and being constrained against axial movement by an outer socketed head 50 and an inwardly spaced collar 5| fixed thereon and bearing respectively against opposite ends of the sleeve. The inner end portion of the shaft 48 is screw threaded for engagement with a nut 52 fixed to the spindle slide 41.

The tool T, which is illustrated as a hob, is fixed on a tool spindle 53 journaled in spaced bearings 54 on the slide 41 with its axis extending longitudinally thereof. One of the bearings 54 l mounted on the slide411er` removal and, for

adjustment-along Suitable 'lf-slots. AThe spinev dle is adaptedto be `drlven,as will be presently described, by mechanism which extends through the spindle slide 41, the'swlvel 35, and the swivel slide 3|.

In the present embodiment, the sw1ve1s1me 3| movement. A piston 58 in the cylinder has av rod 59 extending beyond the rear face of the slide through a packing gland 60 which closes the rear end of the cylinder. The rear or outer end of the rod is rigidly secured, as indicated at 6|y to the left hand column 22. spaced fluid ports 62 and 63 open into opposite ends of the cylinder for draulic system.

An important feature is the provision of means for rigidly clamping the swivel slide 3| in its extended position. In this embodiment, the clamping means is hydraulically actuated. Referring to Figs. 2, 4, 5. and 6, the side walls of the slide have bosses 65 provided with bores 66 that open downwardly and are crossed by the vertical plane of the outer side edges of the slide supporting ways 30 (see Fig. 6). These bores are spaced in 'the direction of slide movement and, as shown, are located approximately at the four corners of the slide. Each side wall between the front and rear bores has a downwardly extending boss 61 (Fig. and an upwardly extending boss 68 (Figs. 4 and 5) provided respectively with cylinders 69 and 10. The cylinders preferably are axially alined.

l Clamping means is associated with each set of bores and cylinders on each side wall and, since the structures on opposite sides of the slide are identical, only one need be described in detail. Each side wall of the slide has a depending guide flange 1i which slidably engages the outer faces, and extends downwardly to approximately the lower face, of its associated way (see Fig. 6). A gib plate 12 is secured, as by means of screw bolts 13, to the lower face of the guide ilange 1| so as to underlie the way 30, and thereby maintain the slide 3| in bearing' engagement with the top of the way. Preferably, a taper gib lil is interposed between the way 30 and the gib plate 12. Each end bore has a clamping plunger l1 slidably mounted therein, and the lower end of the plunger is notched, as at 18, to clear the portion of the way 30 that extends partially across the bore. A threaded stem 19 l extends downwardly from the plunger 11 through the gib plate 12 and through a clamp block or shoe 80 which is seated' in a notch 8| in the top of the gib plate in underlying relation to the taper gib 14. An adjusting nut 82 is threaded on the stem 19 and extends slidably through the gib plate 12 for bear-v ing engagement at its upper end against the clamp shoe 80. Upward movement of theclamping plunger accordingly will movethe shoe to bind the taper gib 80 firmly against the way 30.

The upper end of the clamping plunger 11 extends beyond the end of its supporting boss, as shown in Fig. 5, and is bifurcated, as indicated at 83 to receive the end of a clamping lever 84 which is pivoted to the pin at 85. A hardened block 83 is interposed between the pivoted end of the-lever andthe base of the slot which forms 'the bifurcation, and this block seats at each end in lappropriate recesses 81 in the boss.

clamping lever adjacent the block has an eccen- The f tricor cam-shaped surface 88 thereon arranged in the oscillation of the lever to effect relative movement between the clamping pin and the hardened block. In the present instance, movement of the tree end of the lever upwardly produces an upward movement of the clamping plunger 11.

As shown in Fig. 5, the clamping levers 84 of both clamping plungers 11 on one side of the slide 3| extend toward each other nearly to the axis of the cylinders 69, 10. The cylinders slid,- ably support the opposite ends of a common reciprocable member 89, the end portions of which constitute pistons 9| and 92, respectively. I'he y adjacent ends of the clamping levers extend from opposite sides into a transverse slot 93 formed in the reciprocable member 89, and have arcuate side edges 94 arranged to rock against the upper surface 95 of the slot and against one face of a compensator device by which the clamping forces exerted on the levers vare equalized. The vcompensator 4includes a movable block 96 against which'the levers bear, and this block has an arcuate face S'lseated for rocking movement in a complementary recess in supporting member 90 pinned in position, as at 99, against the lower surface of the slot 03. Aluid passage |00, lili opens to the lower end of the cylinders 10 for admitting iluid under pressure to elevate this member 89 when the slide 3|. is to be vclamped in position, and for exhausting the cylinders when the clamping mechanism is to be released. Similarly, the upper end of the cylinder 59 is provided with a Ifluid passage |02 for relieving the presu sure therein and admitting fluid pressure thereto respectively upon application and release oi' the clamping mechanism.

Means is provided for adjustably determining the extended or advanced position of the swivel slide 3| and its associated parts. Referring to Fig. 7, the slide has aiiixed thereto at one side of center a depending nut |03 for engagement by a screw l 04 disposed in parallelism with the slide ways 30. A tubular shaft |05 rotatably supported in bearing lugs |06 and |01 of the left hand column 22 is axially alined with the screw and receives one lend thereof. The shaft and screw ends are splined to provide for relative sliding and non-rotatable movement. Spaced end thrust bearings |00 and |05 conned on the tubular shaft |05 engage opposite sides of the lug |06. A worm gear H0 disposed between the thrust bearing |09 and a nut iii on the shaft |05 is keyed to the shaft, as lat H2. The shaft |05 is then held against axial movement, and is rotatable by means of the gear ||0. An operating shaft H3 is rotatably journaled on the column 22 transversely of the tubular shaft |05, and carries a worm I4 meshing with the worm gear I0. The outer end of the Shaft ||3 extends through the column (see Fig. l) for manipulation by the operator to effect rotation of the screw |04.

The limits of slide movement are determined' tubular shaft |05. By rotating the screw |04 and thereby adjusting the position of the slide 3| in relation to the stops ||6 and I |8, the extended or operative position of the slide is adiusted and predetermined, and incidentally the retracted position is correspondingly adjusted.

As will presently be more particularly described, the advancing and retracting movements of the swivel slide are used to establish certain relationships in the control system. The shifting collar ||8, is therefore, arranged to swing a lever |20 which is connected through a link |2| with the stem |22 of a pilot'valve mounted in a valve casing |23 (Fig. '1). The lever may be pivotally supported by an arm |24 on the valve casing. The shifting collar ||8 and the lever |20 have a lost motion connection such that the valve will be alternately disposed in its two operative positions as the swivel slide completes its movement respectively into the advanced and retracted positions. An arm |25 fixed for movement with the lever |20 is adapted to engage the end of an actuator |26 for an electric switch housed in a casing |21 upon movement of the slide into retracted position, and to release the actuator upon movement of the slide into advanced position. The switch is arranged selectively to close one or the other of a pair of circuits depending on the position of -the swivel slide.

The work supporting means (refer to Figs. 1, 9,

and 11) The inner face of the right-hand column 2| is provided with a pair of horizontally spaced, vertically extending ways |30 engageable by the vertically elongated workslide 26. At the lower end of the slide is an enlarged hollow casing |3| for supporting the Work spindle for rotation on a vertical axis. The driving mechanism for the work spindle is also largely housed in the casing. Toward its upper end, the work slide has a pair of vertically extending ways |32 on its inner facefor slidably supporting a tailstock |33 which is manipulable through means actuated by the lever |34 to adjust and flx the position of the tailstock.

The work spindle,vas shown in Fig. 9, is rotatably supported on upper and lower casing walls |35 and |36 by combined radial and end thrust bearings |31 and |38, and suitable seals, generally designated |39 are interposed between the spindle and the casing. Within the casing, and between the ends of the spindle, is a worm gear |40 fixed as by a key |4| to the spindle. An adjacent pinion |42 is also secured to the spindle, as by one or more set screws |43.

A feed screw |44 extends vertically through a central portion of the work slide 26, and has screw threaded engagement by an elongated sleeve nut |45 fixed in the upper portion of the slide. The lower end of the feed screw may, by means of a clutch |46, be operatively engaged with mechanism to be described for driving the feed screw at a feeding speed. The upper end of the feed screw |44 is rotatably anchored in the bridge 23 to support the slide 26, as shown in Fig. 1, and is connected with mechanism for driving the feed screw and hence translating the slide at a rapid traverse speed.

The tool spindle drive (refer to Figs. 1, 2, 4 and 12) In the present embodiment, the prime mover for ydriving the various machine elements during the working part of the cycle is an electric motor |50 mounted upon the base 20 within the left-hand column 22. A conventional plural V lock nuts |61.

belt drive |6| connects the motor shaft with a pulley |62 having an elongated hub |63 rotatably journaled in a boss |54 (F18. 2) on the rear wall |65 of the column. Thelnner end of the hub carries a drive gear |56 meshing with a gear |51 (Fig. 12) on the driving shaft of a pump |58 for supplying fluid under pressure to the hydraulic portion of the control system.

A drive shaft |58 extends forwardly of the column through the pulley and hub and is journaled in the front wall |60 of the column. The pulley and hub assembly is rotatable with respect to the drive shaft, but may be coupled thereto by hydraulically actuated clutch means |6|. Thus, as shown in Fig. 2, the end face of the pulley is recessed as at |62. A friction disk |63 is splined, as at |64, for rotation with the pulley. 'I'he rear end portion of the drive shaft is splined, and a fixed clutch element |65 is secured to the end of the shaft by the splines, a split ring |66 and A coacting movable clutch element |68 is located within the pulley recess and slidably engages the splined portion of the drive shaft. Both the fixed and the movable clutch elements carry friction members |68 between which the friction disk |63 is disposed. Springs |10 interposed between the fixed and movable clutch elements exert their force normally t0 hold the elements apart.

The clutch is hydraulically actuated in the following manner. An elongated sleeve |1| is interposed between the pulley hub and the drive shaft, and at one end the sleeve abuts the clutch element |68. 'I'he sleeve is slidably related t0 the pulley hub and the drive shaft, and at its inner end abuts a piston |12 mounted in a cylinder |13 formed in an enlarged portion of a casing |14 that is secured to the drive shaft by such means as a pair of split rings |15. The admission of pressure fluid behind the piston will, through the slidable sleeve |1|, close the clutch |6| and establish va driving connection between the pulley and 'the drive shaft. Pressure fluid is adapted to be admitted to the cylinder |13 behind the piston |12 by a passage |16 formed in the drive shaft. 'The passage communicates with an Iannular recess 11 in a sleeve 18 that encircles the drive shaft and is fixed in a sleeve |18 anchored against rotation, as at |80, to the front Wall of the column. Opposite ends of the sleeve |18 provide seals to prevent the escape of fluid along the shaft |58. Roller bearings |8| are mounted in the casing |18 at opposite ends of the sleeve |18 to support the casing. The recess |11 in the sleeve |18 communicates through a port |82 with a pressure fluid supply passage.

The front end of the drive shaft extends forwardly of the column wall |60 and carries one gear |85 of a pair of pick-off gears. The other pick-off gear |86 is fixed lto the front end of a f |88 and 88 arranged to be selectively engaged` with a complementary gear on the lower end of a vertical drive shaft. Driving engagement of one or the other of the bevel gears |88, |88 with the gear |80 is effected as the machine is being set up for operation, and the engagement will determine the direction of rotation of the tool spindle, the Work spindle and the feed screw. To enable this selective engagement to be easily made, the shaft |81 is, on either side of the bevel gears |88, |88 supported by bearings |8| on stationary parts |82. The bearings permit the shaft to shift axially a distance suiiicient to bring one or the other of the bevel gears into engagement with the gear |90. The front end of the shaft has a shoulder |93 and a nut |94 between which are disposed the inner races of a pair of radial thrust bearings |95. The outer races of these bearings are mounted in a bearing cage comprising a cylindrical member |98 and a plate |91 screw threaded into one end of the cylindrical member and extending radially thereof to form an abutment. The cylindrical member is slidably supported by the front wall of the co1- umn with the plate adjacent the inner face of the wall. The outer end of the sleeve has an annular flange |98 through which the bearing cage may be secured to the front wall by a screw |99. In this position, one of the bevel gears (in this instance the left-hand bevel gear |88) engages the gear |90 and a spacer 2,00 interposed between the pick-off gear |88 and the nut |84 coacts to determine the proper position oi! the pick-off gear to its mating gear.` To effect engagement of the opposite or right-hand bevel gear |89 with the gear |90, the screw |99 and the spacer 200 are removed and the shaft |81 is shifted endwise to the left and maintained in that position by a screw 20| which bears against the column wall and engages the plate on the bearing cage. The head of this screw is accessi- -ble through an aperture 202 in the annular flange |98.

The selective direction of drive afforded by the alternate gears |88, |89 and the gear |90 permits the operator in setting up the machine to effect a feed movement upwardly or downwardly with rotation of the tool and work spindles in a proper direction, These` gears furthermore may be changed in coordination with speed change gears 240 to 243 inclusive (to be hereinafter described) through which the work spindle and feed screw are driven. Thus, selection between the gears |98 and |89 drives the machine elements for la conventional cut either upwardly or downwardly. Selection between these two gears in conjunction with a replacement of the intermediate gears 24|, 242 of the speed change gear train byother intermediate gears including an extra gear for reversing the direction of rotation will condition the machine elements for climb cutting either upwardly or downwardly.

A shaft 203 towhich the bevel gear |90 is aiiixed is journaled on a transverse wall 204 (Fig. 2) of the column and extends vertically into the swivel slide 3| between its supporting ways 30. 'I'he shaft has a bevel gear 205 at its upper end, and below the gear the shaft is mounted in a bearing carried by a bracket 206 which extends endwise .from a cylindrical boss 201 (Fig. 4) into the inner side of the swivel slide. The -boss is mounted on the outer wall of the column and above the bracket supports a radial and end thrust bearing 208 for the hub 209 of a bevel gear 2|0. This gear constantly engages the bevel gear 205 on the vertical shaft regardless of the position of the swivel slide. A shaft 2|| journaled by a bearing 2|2 inthe front wall 32 of the swivel slide 3| is splined in the gear 2| 0 for rotation therewith and for relative axial movement upon adjustment of the swivel slide.

The shaft 2|| is coaxial with the swivel 35, and at its front end carries a bevel gear 2|3 (Fig. 4) disposed beyond the front wall 32 of the slide. The gear meshes with a similar gear 2|4 fixed to a shaft 2|5 which parallels the guideway 46 of the spindle slide 41. At its outer end, the shaft 2|5 carries an elongated pinion 2|6 for engagevtool spindle 53 within a housing 2|8.

ment by a gear 2|1 mounted on the end of vthe Theen# gagement between the elongated pinion 2|8 and the gear 2 I1 is effective through the range of adjustment of the spindle slide 41.

The work drive (nefer to Figs. 1, 2, 7 to 1o incl. and 12) f The vertical shaft 203 that extends into the swivel slide as a part of the driving mechanism of the tool spindle 83 has a power take-off leading to the gearing in the casing |3| through which the work spindle 25 and the feed screw |44 are driven. l i

Referringparticuiarly to Fig. 7, the vertical shaft 203 below the swivel slide and its supporting ways has a pinion` 220 fixed thereon in mesh with an idler pinion 22| supported. as at 222, on the transverse wall 204 and meshing in turn with another pinion 225 on the upper end of a vertical shaft 228. The shaft is supported at its upper end by a bearing 221 on an overhanging portion 229 of the Wall 204,

The gear casing |3| of the opposed work slide includes, as shown in Figs..7, 9 and 10, a forwardly extending housing 229 through which the llower end of the depending shaft 228 passes. In-

side the housing a bevell gear 230 (Figs. I and 10) is slidably splinded to the depending shaft. The bevel gear is journaled in the housing for vertical movement with the work slide. A horizontal stub shaft 23| (Fig. 10) is rotatably mountedv in the housing in bearings 232, and atings 238 in the front wall of the casing. At one end, the rotatable shaft carries a pinion 239 engaging the idler gear 235, and the other end of the shaft extends outwardly of the casing to receive the first gear of a series of speed change gears 240, 24|, 242 and 243. This gear train may be set up for hobbing straight gashes in the work or for hobbing gashes having spiral angles. To accommodate adjustment of the gear train, the intermediate gears 24|, 242 are supported by a stub shaft 244 mounted on an adjustable arm 245 secured, through a split collar connection 246, to a flange 2,41 on the bearing 238.

UThe last gear of the change gear train is secured to one end of a horizontal shaft 249 which is journaled in pairs of end bearings 250. The outer pair of bearings is seated at one end against a shoulder formed in an elongated sleeve 25| and are held in place by a screw threaded cap 252 at the outer end of the sleeve. The inner pair of bearings abut an end nut 253 on the shaft 249 and have a floating relation to the sleeve 25|, a separated relation between said bearings being maintained by a suitable spacer. The end portions of the sleeve are supported in spaced axially alined bores 254 formed in the casing |3|. Suitable means for securing the sleeve to the casing comprises, in this instance, an annular rib 255 (Fig. 10) on the sleeve near the front end thereof arranged to seat in a groove 256 formed in the casing. A clamping ring 251 encircles the end of the casing adjacent to the rib and is seated in a rabbeted groove 258 in the casing. Screws 259, or the like, secure the clamping ring and, in turn, the sleeve to the casing.

The central portion of the shaft has a worm 260 aixed thereon, and the sleeve is cut away to permit engagement of the worm into the wheel |40 on the work spindle 25.

As may be seen in Fig. 9, the axis of the horizontal shaft 249 is eccentrically disposed with respect to the axis of the sleeve 25| so that rotational adjustment of the sleeve will shift the axis of the shaft. Consequently, the worm 260 is adjustable with respect to the worm wheel |40 to provide for wear take-up.

Since the power to the work spindle is derived from a shaft which is a direct part of the tool spindle drive, it will be evident that the tool and Work spindles will be operative or idle depending on actuation of the main clutch |6| and that the spindles will rotate in timed relationship.

The feed drive (refer to Figs. 1, 9, 11, 12)

The gear |42 on the work spindle 25 meshes, as shown in Figs. 11 and 12, with a forwardly disposed gear 26| mounted on the lower end of a vertical shaft 262 having a bevel gear 263 secured near its upper end. The bevel gear engages a bevel gear 264 carried by one end of a horizontal forwardly extending stub shaft 265 that is journaled in bearings 266 in a housing 261 fixed to the casing. A horizontal feed driveshaft 268 extends from front to rear through the casing and is driven from the horizontal shaft 265 through a train of speed change gears 269, 210, 21| and 212. The intermediate gears 210, 21| are preferably mounted on a stub shaft 213 which is supported by an arm 214 having a split collar connection 215 with a flange 216 on the bearing assembly 211 for the front end of the feed drive shaft. The rear end portion of the feed drive shaft 268 is mounted in the casing by a bearing 218. An elongated sleeve 219 surrounds the rear portion of the shaft and is pinned thereto as at 280. A bearing 28| may be interposed between the front end of the sleeve and a boss 282 on the casing. A worm 283 is formed between the ends of the sleeve for engagement with a worm wheel 284 (Figs. 9 and 12) through which the feed screw is driven.

'I'he driving connection between the worm wheel 284 and the feed screw includes the feed clutch mechanism |46. Referring to Figs. 8 and 9, the wormwheel 284 is xed as by screws 285 to a flange 286 on the lower end of a tubular shaft 281 which is rotatably supported on the work slide by interposed bearing bushings 288. The tubular shaft is held against axial movement by the flange 286 and bushing at its lower end and by a nut 289 having screw threaded engagement with the shaft and bearing against a ring 290 which is pinned, as at 29|, to the tubular shaft. Above the nut, the shaft has one member 292 of a positively engageable jaw clutch rigidly secured thereto as by a key 293. The feed screw and the shaft are axially alined, and the lower end of the feed screw extends as shown in Fig. 8 downwardly into the shaft. A lsubstantial portion of the lower end of the feed screw is splined, as shown, for slidable, non-rotative engagement by an assembly which includes the movable clutch member 294 of the clutch. In the present assembly, the member 294 has an elongated hub 295 which is encircled by a clutch shifting ring 296 disposed between a thrust bearing 291 and a fixed ring 298, the parts being adjustably maintained in this relation by a nut 299 screw threaded on the end of the hub and fixed in position of adjustment by set screws 300. A shifting arm 30| extends radially from the shifting ring for connection with means by which clutch actuation is controlled.

Engagement or disengagement of the feed clutch |46 is, in this instance, controlled by the hydraulically actuated means best shown in Fig. 8. The upper wall |35 of the casing adjacent to the tubular sleeve mounting is vertically bored to receive a fixed plug 305 having an upwardly opening cylinder 306 therein. A generally similar plug 301 is fixed to a part 308 of the work slide adjoining the feed screw and a cylinder 300 therein faces downwardly in axial alinement with the lower cylinder. A rod 3|0 has its opposite ends extending as pistons 3|| and 3|2 into the cylinders 306, 309 respectively, preferably through packing glands 3|3. The arm 30| on the shifting collar is pinned, as at 3|4, to an intermediate part of the rod. Pressure fluid is admitted behind the pistons through ports 3|5 and 3|6, the present arrangement being such that admission of pressure fluid behind the upper piston 3|2 engages the clutch and admission of pressure fluid behind the lower piston 3|| disengages the clutch. If desired, the lower piston may be of smaller diameter than the upper piston to provide a pressure differential in favor of the clutch `engaging piston. Since the hydraulic system is sometimes connected to exhaust the pressure fluid from both feed clutch cylinders, the clutch is adapted to be held disengaged by such means as a spring 3|1 encircling the rod 3|0 and bearing between the shifting arm 30| and the packing gland on the lower plug 305.

The rapid traverse drive (refer to Figs. 1 and 12) In the present machine, a rapid return or traverse movement of the work/slide is obtained by a separate drive means for rotating the feed screw |44 in either direction. Thus, the upper end of the feed screw extends into the bridge 23 and has one end gear of a series of speed change gears 3|l, 3|9, 320 and 32| secured thereto. The last gear is fixed to the armature shaft of an independent rapid traverse motor 322 mounted within the upper part of the right-hand column 2|.

Operation of the rapid traverse mechanism and the direction of its movement during any part of the operative cycle of the'rmachine is controlled and determined by means to be presently described.

The coolant system (refer to Fig. 1)

A separate'electric motor 323 mounted on the base 20 within the right-hand column is provided for driving a coolant pump 324 located in the base.

Coolant uid from the pump is delivered through a conduit 325 which runs upwardly along the right-hand column and terminates in a flexible end portion 326.

A discharge nozzle is arranged to be adjustably secured, as to the slide swivel 35, in position properly to discharge coolant fluid over the tool and work. Such fluid subsequently drains into a collector 328 in the base.

Operation ofthe coolant system is determined by controls which permit the system to be rendered inoperative or conditioned for automatic operation during the cycle.

cmtroz means (refer to Figs. 1, 14, 16 and 17) The control means in the present instance is disposed in a casing 329 (Fig. l) suitably secured to the front side of the right-hand column 2|. The several controls as they appear in Fig. 1 in clude start and stop push buttons 330 and 33| controlling switches for initiating and discontinuing machine operation: push buttons 332 and 333 for actuating switches energizable to effect respectively rapid traverse upwardly and downwardly; a selector member 334 having three positions for determining under certain operative conditions the direction of rapid traverse up or down, or an open circuit; a selector member'335 for manual control of the operation of the coolant system; a cycle lever 331 for initiating cyclic operation of the machine; a feed lever 338 for discontinuing the feeding movement of the work carriage; a motor clutch lever 339 for establishing a driving engagement through the main motor clutch |6| independently of the cycle; a stop cycle 'lever 340 for interrupting the cycle at any time;

and a. controller 34| adapted to be actuated by the work carriage or slide 26 at predetermined limits of its movement. 'I'he operations and functions of these various controls will hereinafter be more particularly described.

'I'he controller and its associated structure, as shown in Fig. 14, embodies a shaft 342 suitably journaled in the casing with one end thereof extending froin the casing to a position adjacent the work slide. This end of the shaft has an arm 343 intermediately fixed thereon which at opposite ends supports antifriction rollers 344 and 345. The arm in the neutral position of the shaft extends substantially in parallelism with the direction of carriage movement, and the rollers thereon project into the path of a pair of dogs 346, y341 mounted on a dog bar 349 on the slide 26 for adjustment along a slot 348 (Fig. 1). The dogs have beveled surfaces 350 (Fig. 14) for roller engagement and arranged to rock the shaft in opposite directions out of neutral when the upper and lower dogs engage'their corresponding rollers.

Means is provided for urging the cam shaft 342 yieldingly into neutral position. To this end, the shaft has fixed thereto a pinion 35| for engagement with a short gear rack 352 on a block 353 secured, as at 354, to a rod 355. 'I'he rod is elongated to extend through an adjacent part of the casing wall and is provided with a head 356 on its outer end. A sleeve 351 is interposed between the rod and the casing wall and bears at its outer end against the rod head. The inner end of the sleeve has a flange 358 fitting a recess 359 in the wall. A helical compression spring 360 surrounds the rod and bears respectively against the flange 358 and a bearing 36| for the block end -of the rod. As shown, the sleeve is longer than the width of the wall through which it extends to permit reciprocating movement of the sleeve and rod to the extent determined by the rod head 356 and flange 358.

The bearing 36| is slidably supported by a stem 362, mounted on the casing, for movement in one direction only from a neutral position, as determined by an adjustable nut 363 on the stem, to compress the spring 360. Rotational movement of the shaft in one direction (for example clockwise as viewed in Fig. 14) acts through the pinion 35| and rack 352 to shift the block 353 and slidable bearing 36| to the left against the force of the spring 360. When the shaft is released the spring urges the parts to their initial or neutral position, the limit being the abutment between the sutiable bearing 36| and nut ass. Rotation of the shaft in a counterclockwise direction shifts the block 353, rod 355 and sleeve 351 to the right, again compressing the spring'between the'fiange on the sleeve and the now stationary bearing 36|.

Release of the shaft returns the parts to their initial position, as determined by the-engagement between the sleeve flange andthe casing wall.

The shaft 342 may be, considered a cam shaft since it carries a doubleended barrel or sleevetype cam 364 having at one end substantially diametrically spaced rising cam surfaces 365 circumferentially facing each other constituting a part of the cycle control system, and similar oppositely acting rising cam surfaces 386 on the other end forming a part of the rapid traverse con` trol system. The cam shaft also carries a cam 361 in operative association with an actuator 388 for a switch 369 and another cam 310 operatively engaging the actuators 31| and 312 of a pair of switches 313, 314 respectively. The relationship of these cams to each other, to the cam shaft, and

the arm is arranged to ride on the outer end of a valve stem 380. This valve stem is a part of the control valve for the main driving clutch I8 Thecycle lever shaft also has secured thereto a sleeve 38| carrying a projecting member 382, such as a headed screw, for engagement with an actuator 383 for a switch 384, and a similar member 385 for engagement with an actuator 386 of another switch 381.

The sleeve also carries a projection 388 arranged to ride over a cam 389 formed at the end of a finger 390 on an arm 39|. The arm is pivctally supported, as at 392, and a spring 393 is arranged to exert its tension on the end of the arm opposite the finger to hold the cam against the projection and to maintain a headed member 394 normally out of engagement with an actuator 395 for a switch 396. The swinging arm 39| has a ledge 391 near the finger 390 for engagement, when the arm is depressed by coaction between the cam and projection, by the' hooked end of an extension 398 integral with a cam follower 399. Spring means 400 urges the extension toward a position for engagement lwith the ledge.

The cam follower 399 is xedto a shaft 40| l which is supported by the `casing for oscillatory movement as well as limited axial movement. The shaft is so disposed that the cam follower 399 thereon may by axial movement of the shaft be shifted into and out of operative association with one of the rising cam surfaces 366 on the g cam sleeve 364. A similar cam follower-402 is pinned to the shaft for similar movement into and out of association with the diametrically spaced surface 366, the'two cam followers being so arranged (see Fig. 15) that one or the' other will be selectively disposed in engagement with its associated cam by axial movement of the shaft. The two operative axial positions of the shaft are suitably determined by spaced grooves and a the sleeve has the clutch lever 339 pinned thereto and the inwardly projecting sleeve end carries an arm 401, the free end of which extends into an elongated notch 408 (Fig. 14) appropriately formed in the clutch control valve stem 380. This arrangement permits the clutch valve to be manipulated independently of the remaining controls for effecting engagement of the main motor clutch, thus permitting the work and tool spindles to be driven momentarily as the machine is being set up. lSince this machine movement is only infrequently used, the clutch lever is preferably latched normally in an idle position by such means as a spring pressed plunger 409 carried by the lever for holding engagement with a recess 4|0 in the casing wall. The valve stem may move freely when the arm 401 is latched.

The cycle control valve stem 318 is latched in theposition to which it is shifted by such means as a latch 4|5 pivotally supported by a stud 4|6 and having a nose 4|1 for engagement with a notch 4|8 in the cycle valve stem. A spring 4|9 bearing against the tail 420 of the latch is arranged to urge the nose into notch engagement. The latch is released from its engaged position by means which may be manually actuated through the stop cycle lever 340, or automatically in response to a. proper movement of the cam shaft 342. The stop cycle lever is on a shaft 42| supported by oscillation by the casing, as well as for axial movement between two positions determined by a detent arrangement designated 422 (Fig. 15). The stop cycle shaft carries a pair of spaced arms 423 and 424 having rollers 425 thereon for engagement with the rising surfaces 365 on the barrel cam. These rollers constitute cam followers spaced on the shaft 42| and adapted to be alternatively positioned for engagement with the associated rising cam surfaces 365, this engagement depending on the axial position of the stop cycle shaft (see Fig. 15). As shown in Fig. 15, the spring means 400, which acts on the extension 398, may also be connected to the cam follower 424 for holding the selected cam follower in engagement with the sleeve cam 364.

One of the cam followers (in this instance the cam follower 423) has an angular projection 421 engaging the tail 42|] of the latch for disengage ably swinging the latch when either cam follower is moved by the sleeve cam, or when the stop cycle lever is manually rocked.

The feed lever 338 is on a shaft 428 journaled in the casing for rocking movement, and an arm 429 on the shaft is connected through a linkage 430 with the stem 43| of a feed control valve. A detent device 432 holds the feed valve stem in one of two positions. The feed lever shaft also carries a headed member 433 for engagement with an actuator 434 for a switch 435.

Hydraulic system (refer to Fig. 16)

The hydraulic part of the control system includes a cycle control valve A, a clutch control valve B, a feed valve C, and a control valve D, the position of which is determined by the pilot valve E at the swivel slide 3|. Each of these valves in the present embodiment has only two positions, namely, a, starting position in which the valves are disposed as shown in Fig. 16, and operative positions into which the valves are shifted by manipulation of the various control elements associated therewith, or, as to the control valve, by the position of the pilot valve.

The pump |58, which is continuously driven when the main drive motor |50 is running, draws fluid from a sump 439 through a pump intake line 440 and delivers the uid under'pressure to a pressure line 442. The cycle valve includes a casing 44| having a series of fluid lines 443 to 453, inclusive, connected to parts therein, and a spool type plunger 454 joined to the stem 318 and having a. series of grooves 455 to 459, inclusive, therein. The valve plunger is normally urged in one direction by spring means 460, and is held in its other position against the tension of the spring by the latch 4|5. In its idle position, as shown in Fig. 16, the pressure line 442 is connected with the port 63 of the cylinder and piston 51, 58 (through the lines 442, 445, groove 456, and lines 444, 46| to port 63).

When upon actuation of the cycle lever shaft 315, the plunger 318 is depressed and latched, the pressure line connection ls reversed to admit pressure fluid to the port 62 on the advancing side of the swivel slide cylinder and piston (through lines 442, 445, groove 456, and lines 446, 462 to port 62). port 62 (comprising 462, 446, 451, 441 to a sump return line 463) is interrupted, and the port 63 is connected to the return line (through 46 I, 444, 455 and 443 to 463). These connections admit pressure fluid to advance or retract the swivel slide 3|, and it may be noted that in the idle position of the cycle valve the pressure line is connectedto maintain the swivel slide in its retracted position.

The clutch control valve structure includes a casing 464 having ports' connected respectively with the pressure line 442, a line 465 and the drain line 466, and a spool type plunger 461 connected with the stem 380 and urged into an idle position by a spring 468. The plunger has a groove 469 and a clearance 410 about the spring. In the idle position, the groove 469 is positioned to block the pressure line 442, and the line 465 is connected to the drain line 465 so that the clutch |6| is disengaged. When the cycle lever shaft is actuated and latched the clutch valve plunger is simultaneously shifted, and a pressure connection is established to vthe main drive clutch cylinder |13 (through 442, 469, 465, |82, |11 and |16). Thus the driving connection between the `main driving motor and the driving transmission is established and the tool and work spindles are set in motion. As previously mentioned, manipulation of the clutch lever will manually shift the clutch valve plunger to permit the' tool and work spindles to be operated independently of the rest of the control system. l

'I'he pilot valve is a reversing valve, and its casing |23 has ported connections with the pressure line 442, with lines 41|, 412, and with a relief line 413. The spool type plunger 414 has grooves and end clearances 415, 416 and 411. In the idle position of the machine, the valve connects the pressure line 442 with one end of the control valve (through 415 and 41|), and the relief line 413 with the opposite end of said control valve (through 412 and 411). The plunger 418 of the control valve is freely mounted in the valve casing 419 for movement to either end of the casing as pressure fluid is admitted to the opposite end. The control valve plunger has grooves 484, 485 and 486, and the casing is ported to communicate withpressure line 442, at the ends with lines 41|, 412 from the pilot valve, with near either end with the drain line 463.

Also, an exhaust connection from they When the pilot valve is in idle position, as shown, the control valve plunger 418 is held by pressure fluid in a position in which a connection is established to the cycle control valve (through 442, 485 and 452), but this line is blocked by a land 481 on the cycle valve plunger.

The control valve during the cycle determines and, in effect, times the admission of pressure .The spool type plunger 49| which is fixed to the stern 43 I, has grooves 492 and 493.

The feed control valve is normally located in its operative position, that is to say, in a position in which it enables operation of the feed and clamping of the swivel slide. Its second position is one to which it is shifted by the intentional hand manipulation of the feed lever,

'and in this position the valve prevents feed and clamping.

The line 489 is common to the unclamping cylinders 69 on the swivel slide 3| and the -feed clutch disengaging cylinder 306. The line 490l is common to the clamping cylinders 10 and the feed clutch engaging cylinder 309. In the operative position of the feed valve, as shown, and with the cycle control valve in its idle position, the unclamping cylinders of the clamping devices and the disengaging cylinder of thefeed clutch are connected with the drain line (through 489,492, 45|, 459, 450 and 484 to 463). Also, the clamping cylinders and the engaging cylinder of the feed clutch are connected with the drain line (through 490, 493, 449, I458 and 448 to 463).

After the cycle lever shaft has been actuated to depress and latch the cycle control valve stem 318, the last portion of the advancing movement of the swivel slide toward itsA operative position will, through the linkage |20, I 2|, |22, shift the pilot valve. The responding movement of the control valve effects the admission of pressure fluid to the actuating mechanism which clamps the swivel slide 3| in its advanced position and initiates operation of the feed screw (from 442 through 450, 458, 449, 493 and 490 to cylinders 'I0 and 309). The hydraulic means for unclarnping the clamping mechanism and disengaging the feed clutch remain connected to the return line (from cylinder 69 and 306 through 489, 492, 45|, 459, 452 and 486 to return line 463).

The machine and control elements remain in this condition until the cut is completed or the feed part of the cycle interrupted by a manipulative act. Return of the parts to their idle position is initiated by tripping the latch 4|5 to permit the cycle control valve and the clutch valve to be moved to their idlepositions by the springs 460 and 468, respectively. The shift ofv the clutch control valve again blocks the pressure line 442 from the cylinder |13 and connects the latter with the return line (through 465,'410 and 466). The connections to the feed clutch cylinders 306 and 309 and to the clamping cylinders 69 'and 10 are reversed as the cycle control valve plunger 454returns to its idle position to connect the unclamping cylinders 69 and the pressure uid line' (through 442, 450, 459, 45|, 492 and 489), while the clamping cylinders 10 and the feed clligen-ingagingl cylinder309 are ,feed clutch disengaging cylinder 306 with the connected to the return line 463 (through 490, 493, 449, 458, and 448). The connections leading to the swivel slide cylinder 51 are also reversed in the cycle control valve, the port 63 to the retracting side of the piston being then connected with the pressure line 442 (through 445, 456, 444 and 46|) and the port 62 to the advancing side of the Apiston'being connected with the return line 463 (through 441, 451, 446 and 462).

Disengagement of the main clutch stops rotation of the spindles. AS the swivel slide 3| reaches its retracted position the pilot valve is shifted to reverse the connections to the control valve and return this valve to its idle position in which, as above mentioned, the unclamping and clamping cylinders and the feed clutch engaging and disengaging cylinders are all connected with the return line 463.

When the feed control valve is shifted by manual actuation of the feed lever, the connections through the valve are reversed. Hence, if the feed lever is actuated during a cycle and while the swivel slide 3| is clamped in advanced position and the feed clutch engaged, the reversel will admit pressure fluid for unclamping the swivel slide and disengaging the feed clutch (through 449, which is then connected to the pressure line, 492 and 489), and will exhaust the slide clamping and feed clutch engaging cylinders (through 490 and 493 to 463). Should the feed lever be shifted from its operative position at any time other than when the machine is in cycle, a connection of both common lines 489, 490 to the return line will result (from line 489, through 492,449, 458, 448 to 463, and from line 490 through 493 to 463) Electric control (refer to Figs. 16 and 1 7) The electrical control system embodies circuits for energizing and deenergizing the main driving motor, the coolant pump motor, and the rapid traverse motor, and with particular reference to the latter, includes selectively energizable circuits therefor which are enabled or disabled depending on the operative condition 'of the machine and, in part, on connections established manually by the operator.

In the present embodiment, the reference characters LI, L2 and L3 indicate the three electric power lines from a three phase source of supply'. Only the lines LI and L3 are used in the control system. An energizing circuit for the main driving motor |50 is controlled by a main relay switch MR having contacts CRI, CB2 and CR3 for the power lines; contacts CR4 for connecting the power line L2 to the rapid traverse motor 322; and contacts CR5 in a holding circuit for the relay winding MRW. The starting push button 330 controls the normally open switch'SI and the stop push button 33| controls a normally closed switch S2, and these switches are connected in series in the energizing circuit of the relay Winding MRW to close the circuit whenv the starting push button is actuated and open the holding circuit when the stop" push button is depressed.

The rapid traverse motor 322 is capable of operation in reverse direction and energization thereof is immediately controlled by a pair of relay switchesv RI and R2, the switch levers of which are linked together as at 500 to insure alternate operation. `In the relay switch RI are contacts CII and CI2 for closing a circuit from the power lines LI and L3 to energize leads 50| and 502 leading to the rapid traverse motor, It will be considered that the circuit controlled by this relay switch effects rapid traverse movement in an upward direction. The other relay switch R2 has a similar pair of contacts C2I and C22 arranged to connect the power lines LI, L3 to the motor lines 50|, 502 in a reverse direction. This circuit will effect rapid traverse movement downwardly. Each of the switches RI and R2 include holding contacts CI3 and C23, respectively, for establishing a holding circuit through energizing windings WI and W2 of the relay switches. Each relay switch also includes a pair of normally closed contacts C I 4, C24, respectively, which are connected in series and control energization of the winding W3 of a time delay relay R3. Y A,

The time delay relay is a part of the system for controlling the operation of a brake for stopping rotation ofthe rapid traverse motor at the moment the energizing circuit to theI motor is broken. In this instance the braking means preferably includes a motor brake 503 which is held in applied condition by' springs 504 and is maintained out of brake-applying condition by energization of a solenoid 505. The solenoid is connected to thepower mains through contacts C4I, C42 of a relay switch R4 having an energizing winding W4. Energization of this winding is controlled by contacts C3I on the time delay relay R3. A'I'he arrangement is such that when the machine is in operation the solenoid control contacts C4I and C42 are closed, and the brake held inoperative. When either of the rapid traverse relay switches moves to open contacts CI4 or C24, the time delay relay R3 is deenergized', and a holding circuit for the solenoid switch relay R4 is established through the then closed contacts CI3 or C23. When subsequently the closed rapid traverse switch is opened to break the rapid traverse motor circuit, the holding circuit of the solenoid relay is also broken to deenergize the brake solenoid 505 and permit the springs 504 to set the brake. At approximately the same time the holding circuit of the time delay relay R3 is closed to reestablish the solenoid control relay holding circuit. However, the time delay relay is set to retard closing the circuit controlled thereby for a period sufficient to enable the brake to stop the rapid traverse motor. Consequently, the solenoid brake is applied only after deenergization of the rapid traverse motor and then only momentarily. It is therefore not possible to impose the load of. the brake on the feed screw during a feeding operation.

Energization of the windings of the relays RI or R2 is selectively controlled by a plurality of switches, certain of which are arranged for mannal actuation and others for correlation with various parts of the machine and the control means. The switch |21 which is responsive to swivel slide movements is of the single pole, double throw type and includes contacts 506 and 501 which are closed respectively when the swivel slide is in its retracted and advanced positions. The contacts 506 control a circuit by which rapid traverse movement may be obtained in either direction` by manual control. The contacts 501 control a, circuit by which the rapid traverse movement is automatically initiated at the end of a cutting operation to return the work carriage to its starting position.

Considering manual operation, the rapid traverse up and rapid traverse down push buttons 332 and 333 are arranged to close normally open switches 508 and 509, respectively, which selectively control circuits to the energizing windings WI and W2 of the rapid traverse up and down relays RI and R2, respectively. To avoid damage to the machine which might occur, should the operator unintentionally depress either rapid traverse button when the work carriage is at the end of its travel in the corresponding direction, means is provided which disables the circuit by which the work slide 26 might be moved beyond either limit. In this instance this result is obtained by interposing the switch 369 (of the normally open type) in the circuit between the manual rapid traverse up switch 508 and the rapid traverse relay winding WI. When this switch is open the relay winding cannot be energized by manipulation of the push button 332. Similarly, the switch 314 of the same type is interposed in the circuit between the manual rapid l spectively, disposed, in the neutral position of the -cam shaft, to engage the switch actuators 368 and 312 and hold the switches closed. The cams are so arranged that rotary movement of the cam shaft 342 in one direction or the other will shift the high point' on one cam out of engagement with its switchactuator, while maintaining engagement between the other cam and its associated actuator. Thus when the cam shaft has been rocked by either limit dog on the work slide 2li, one or the other of the switches 369 and 314 will be opened, depending on the direction of rocking movement of the cam shaft. As shown, the switches and their actuating cams are so arranged that rocking of the cam shaft by the. lower dog 341 v at the limit of upward travel of the work carriage opens the switch 369, while movement of the camshaft by the upper dog 346 opens the otherrswitch 314.

Rapid traverse cannot be manually initiated while the feed lever is in its operative position unless the cycle lever shaft 315 is in its inoperative position and the swivel slide 3| retracted. The member 433 on the feed lever in the operative position thereof is arranged to engage the switch actuator 434 to close contacts 5I2 of the single pole double throw switch 435 and establish a circuit between both of the manual rapid traverse switches 508, 509 and the normally open switch 384, the condition of which is determined by the position of the cycle lever shaft. This latter switch 384 is closed by the member 382 only when the cycle lever shaft is in its idle position, and the cricuit controlled by this switch is the rapid traverse circuit which is closed by the switch 506 only when the swivel slide 3l is in its retracted position. These contacts 506 are connected in series with the switch 384 (Fig. 17) and contacts SI2 of switch 435 and with the safety switch 313 which controls the connection of the circuit with the power line LI.

The safety switch is of the normally open type and is held closed by engagement of the actuator 31| with a high point 5I3 on the cam 310. The purpose of the safety switch will be hereinafter more fully described.

A second circuit enabling manual control may be set up when the swivel slide is advanced and the opposite contacts 501 of the switch |21 closed.

-This circuit can only be energized when the feed lever has been shifted to the position in which it disengages the feed clutch -and unclamps the swivel slide. Such movement of the feed lever opens contacts 5I2 and permits the opposite corn tacts 5|4 to close, thereby establishing a control 

